Corrosion Inhibitive Properties of 5-(4-Aminophenyl)-1,3,4-oxadiazole-2-thiol and 5-(4-Methylphenyl)-1,3,4-oxadiazole-2-thiol on Mild Steel in 1.0 M HCl Solution

Abstract

The corrosion inhibition consequence of 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol (APOT) and 5-(4-methylphenyl)-1,3,4-oxadiazole-2-thiol (MPOT) were accomplished by employing weight loss measurement, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurement and scanning electron microscope (SEM). An impact of immersion time 12.0 h and different temperatures (298, 308 and 318 K) with solution of 1.0 M HCl, which include various concentration of inhibitor at the corrosion of mild steel were designed. Weight loss measurement showed that with enhancing the concentration of these studied inhibitors the percentage inhibition efficiency (IE%) enhances, but corrosion rate (CR) diminishes while reverse condition in case of temperatures change. The electrochemical impedance spectroscopy examine pointed out that the charge transfer resistance (R_ct) values enhances and consequently the double layer capacitance (C_dl) values diminishes with rising each inhibitor concentration in 1.0 M HCl and also there is a formation of adsorption coating at the metal surface. Polarization measurement showed that both APOT and MPOT perform as mixed type corrosion inhibitors. Furthermore, the adsorption behaviour on surface of mild steel for each studied inhibitor results the Langmuir adsorption isotherm. Surface conduct of mild steel also designed through the SEM and energy dispersive X-ray (EDX) analysis and concludes that there is evolution of inhibitive film of APOT and MPOT on the surface of mild steel.